Now this is gonna be a big wall of text so brace urself
this is a list of things i thought of which would be cool i guess

Currency:

now this game doesn't really have a currency but instead it has gold
what if instead of gold you could mine Iron in your city
and instead of using gold as currency to interact with NPC's use "gold coins"
now why may you ask ?
making gold coins something you can only gain from NPC's will force you to interact with the NPC's to be able to buy mercs, making mercs more of a reward you get from doing quests and/or trading with NPC's
diplomacy would be based of your efforts with NPCs and not how many sheep you have or gold you mine
upgrades in your city which require gold will require you to do quests or fight players/NPC for "gold coins"
YAY you now have to interact with the game world!

Items:

now items are always fun !
giving you more customization / ability to further empower your troops
here is a few points i thought of to do with items:
-Make items in your town from materials like Iron and wood or other future resources
-buy items from NPC's with "gold coins"
-loot items from other players there corpses
-loot rare items from hard NPC castle sieges
-give items diff looks to your units
-make for example armors which give your troops fire imunity at cost of defensive/offensive stats to counter dragons
-items make your normal units stronger but at the cost of loosing the item when the unit dies, this highers the stakes in a fight with geared units
-adds more strategic options to the game and ways to surprise your enemy's

Generals:

Generals would be units a bit like your hero only then less combat orientated but more buff orientated
they boost the surrounding troops but dont have any offensive powers
it would be cool aswell for example to allow generals to make your army taunt your enemys
making them all cheer or roar or drum or whatever
~lord of the rings movie pops into my mind~~~~ ^^
you could also make it that you need a general to use a army for combat
i mean... can you rly fight a enemy without a leader ?

Barracks:

a building you can store troops inside of
when my keep is fully equipped with 90/90 army for incoming sieges it sorta makes trading / making extra units difficult
it be nice if you could build a building which you could use to store army's in which you aint using
it will also save me from having 4 army's wandering about as storage for troops / units im not using

Resource capacity:

now i don't have a problem with the resource cap but it would be nice if there was a way to store some elsewhere without having to make army's of horsecarts
iv suggested before making a bank inside NPC towns to store spare gold
but if we go from the currency model up above you could remove the cap from currency all together because its no longer a resource and not generated at your town / work camps anymore
it still be nice to have a bank tho to store other spare resources
tho i believe there should be some sort of cost at it
maybe a tax on the resources you store, or a fee of "gold coins"

Army's:

Army's at the moment are a cluster of random units you choose to bring upto a cap of 60
now as stight forward as it is it sorta brings a few issues with it
-if the units are taken out it disappears
-you can bring 4 dragons...
-you can bring 60 horsecarts and turn army's into giant banks
-units have to be able to carry storage cap or else it forces players to bring horsecarts instead of army to carry loot
-cuz army's disappear without units in it you cant add any customization to it because it will be erased all the time

what i would like to see is that players are able to "build" army's
-to create a army it would cost lets say 4 horse carts and 4 workers (as example)
-the army would have a set resource cap (maybe like 4000)
-the army could have different unit groups for example 0/60 normal units 0/3 generals 0/1 dragons (or superunits if anything else then dragon gets added later)
-the army wont be destroyed if no units are inside only if you deside to destroy it
-you could name it / choose icon / banner / etc to make army's distinguishable
-give a player a free army when they start the game so they don't need to build the carts / workers first to be able to venture out into the world
-give army's a inventory so they can carry looted items

this way you can cap unit types by grouping them and make army's proper entity
and stop horsecart army's / dragon army's

World map

now when i first saw this game the first thing that popped into my mind was
heroes of might and magic 3 + stronghold
now the worldmap in HMM3 was amazing, it would not only get you from point a to b
but it had allot of features which you could interact with
it would be cool if there was more then just emptiness and NPC city's on the worldmap
but all sorts of locations to visit like dungeons / interesting buildings / pvp related stuff like battlefields / player meeting spots / just random fun textures to spice it up a lilbit

then again im sure stuff like that will appear over time :P

Few Random things:

-a formation like the one the Romans used to use were they use there shields above there heads and sideways and walk really close together
i would make them immune from arrows but very slow + it would look fun (mainly because it looks fun ^^ )
-make hoardings shape with the walls so it looks more natural + give towers the option for hoardings (hinting at pointy tipped towers, its dawn of "fantasy" after all)
-give square towers something special to them... they seem sorta.. sad and lonely
-moats
-tunneling?! could be fun
-effects from buffs / heals / etc so you know when something is active and when it runs out without having to stare at the right unit its info screen
-cast radius indicator on the floor when mouse-over a units aoe spell which has a radius so you can see how far the effect reaches

Final words:

now most of the idea i posted sorta tie into eachother a lil
i sorta bunched it all together from older posts iv made / posts of other peeps who inspired me
this is what i would do with the game, feel free to rip it apart or spit upon it
hope it inspires someone somewhere atleast
or at least be a interesting read